Polymerized lithium ion battery cells and modules with overmolded heat sinks

ABSTRACT

A lithium ion (Li-ion) battery cell includes a prismatic housing that includes four sides formed by side walls coupled to and extending from a bottom portion of the housing. The housing is configured to receive and hold a prismatic Li-ion electrochemical cell element. The housing includes an electrically nonconductive polymeric (e.g., plastic) material. Additionally, a heat sink is overmolded by the polymeric material of the housing, such that the heat sink is retained in an outer portion of the sides of the housing and the heat sink is exposed along the bottom portion of the housing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from and the benefit of U.S.Provisional Application Ser. No. 61/746,836, entitled “VARIOUSEMBODIMENTS OF PLASTIC OR POLYMERIZED BATTERY MODULES”, filed Dec. 28,2012, which is hereby incorporated by reference for all purposes. Thisapplication relates to, and is hereby filed concurrently with, U.S.patent application Ser. No. ______, entitled “POLYMERIZED LITHIUM IONBATTERY CELLS AND MODULES WITH PERMEABILITY MANAGEMENT FEATURES”, withinventors Matt Tyler and Kem Obasih, U.S. patent application Ser. No.______, entitled “POLYMERIZED LITHIUM ION BATTERY CELLS AND MODULES WITHTHERMAL MANAGEMENT FEATURES”, with inventors Kem Obasih and Matt Tyler,and U.S. patent application Ser. No. ______, entitled “WELDINGTECHNIQUES FOR POLYMERIZED LITHIUM ION BATTERY CELLS AND MODULES”, withinventors Matt Tyler and Kem Obasih, all of which are herebyincorporated by reference for all purposes.

BACKGROUND

The disclosure relates generally to the field of batteries and batterymodules. More specifically, the present disclosure relates topolymerized (e.g., plastic) lithium ion batteries and battery modules.

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present disclosure,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentdisclosure. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

A vehicle that uses one or more battery systems for providing all or aportion of the motive power for the vehicle can be referred to as anxEV, where the term “xEV” is defined herein to include all of thefollowing vehicles, or any variations or combinations thereof, that useelectric power for all or a portion of their vehicular motive force. Aswill be appreciated by those skilled in the art, hybrid electricvehicles (HEVs) combine an internal combustion engine propulsion systemand a battery-powered electric propulsion system, such as 48 volt or 130volt systems. The term HEV may include any variation of a hybridelectric vehicle. For example, full hybrid systems (FHEVs) may providemotive and other electrical power to the vehicle using one or moreelectric motors, using only an internal combustion engine, or usingboth. In contrast, mild hybrid systems (MHEVs) disable the internalcombustion engine when the vehicle is idling and utilize a batterysystem to continue powering the air conditioning unit, radio, or otherelectronics, as well as to restart the engine when propulsion isdesired. The mild hybrid system may also apply some level of powerassist, during acceleration for example, to supplement the internalcombustion engine. Mild hybrids are typically 96V to 130V and recoverbraking energy through a belt or crank integrated starter generator.Further, a micro-hybrid electric vehicle (mHEV) also uses a “Stop-Start”system similar to the mild hybrids, but the micro-hybrid systems of amHEV may or may not supply power assist to the internal combustionengine and typically operate at a voltage below 60V. For the purposes ofthe present discussion, it should be noted that mHEVs typically do nottechnically use electric power provided directly to the crankshaft ortransmission for any portion of the motive force of the vehicle, but anmHEV may still be considered as an xEV since it does use electric powerto supplement a vehicle's power needs when the vehicle is idling withinternal combustion engine disabled and may recover braking energythrough an integrated starter generator. In addition, a plug-in electricvehicle (PEV) is any vehicle that can be charged from an external sourceof electricity, such as wall sockets, and the energy stored in therechargeable battery packs drives or contributes to drive the wheels.PEVs are a subcategory of electric vehicles that include all-electric orbattery electric vehicles (BEVs), plug-in hybrid electric vehicles(PHEVs), and electric vehicle conversions of hybrid electric vehiclesand conventional internal combustion engine vehicles.

Vehicles using electric power for all or a portion of their motive powermay provide numerous advantages as compared to traditional vehiclespowered by internal combustion engines. For example, vehicles usingelectric power may produce fewer pollutants and may exhibit greater fuelefficiency. In some cases, vehicles using electric power may eliminatethe use of gasoline entirely and derive the entirety of their motiveforce from electric power. As technology continues to evolve, there is aneed to provide improved power sources, particularly battery modules,for such vehicles.

Vehicles using electric power for at least a portion of their motiveforce may derive their electric power from multiple individual batterycells, which may be packaged into battery modules. In particular,multiple lithium ion battery cells or cell elements may be packaged intobattery modules. Lithium ion battery cells or cell elements and theirassociated battery module(s) may operate at elevated temperatures (e.g.,between 0 and 85° C.) compared to traditional lead acid batteries, sothey are typically packaged in a material that facilitates cooling.Also, lithium ion cell elements are particularly susceptible to oxygenor moisture, so they are typically packaged in a hermetically sealedmetal housing. However, due to the limitations of metal fabrication,form factors are similarly limited. Accordingly, there is a need foraddressing thermal management and permeability concerns described abovein a cost effective manner that enables efficient production methods andtechniques.

SUMMARY

Certain embodiments commensurate in scope with the disclosed subjectmatter are summarized below. These embodiments are not intended to limitthe scope of the disclosure, but rather these embodiments are intendedonly to provide a brief summary of certain disclosed embodiments.Indeed, the present disclosure may encompass a variety of forms that maybe similar to or different from the embodiments set forth below.

Present embodiments of the disclosure are related to a lithium ion(Li-ion) battery cell including a prismatic housing that includes foursides formed by side walls coupled to and extending from a bottomportion of the housing. The housing is configured to receive and hold aprismatic Li-ion electrochemical element. The housing includes anelectrically nonconductive polymeric material. Additionally, a heat sinkis overmolded by the polymeric material of the housing, such that theheat sink is retained in an outer portion of the sides of the housingand the heat sink is exposed along the bottom portion of the housing.

Embodiments of the present disclosure are also directed to a lithium ion(Li-ion) battery module including a container with one or morepartitions extending from a bottom portion of the container to definecompartments within the container. Each of the compartments isconfigured to receive and hold a prismatic Li-ion electrochemicalelement. The container includes an electrically nonconductive polymericmaterial. Additionally, a heat sink is overmolded by the polymericmaterial of the container such that the heat sink is retained in a firstportion of the container and is exposed along the bottom portion of thecontainer.

Present embodiments of the disclosure are also directed to a method formanufacturing a lithium ion (Li-ion) battery module. The method includesovermolding a heat sink with an electrically nonconductive polymeric(e.g., plastic) material to form a container. The container includes oneor more partitions extending from a bottom portion of the container. Theone or more partitions define compartments within the container. Thecompartments are configured to receive and hold prismatic Li-ionelectrochemical elements. Additionally, the heat sink is overmolded suchthat the heat sink is retained in a portion of the container and isexposed along the bottom portion of the container.

DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a perspective view of an embodiment of a vehicle having abattery module to provide power for various components of the vehicle,in accordance with the present techniques;

FIG. 2 is a cutaway schematic view of an embodiment of the vehicle andthe battery module of FIG. 1, in accordance with the present techniques;

FIG. 3 is a partial exploded perspective view of an embodiment of thebattery module for use in the vehicle of FIG. 1, in accordance with thepresent techniques;

FIG. 4 is a partial exploded perspective view of another embodiment ofthe battery module for use in the vehicle of FIG. 1, in accordance withthe present techniques;

FIG. 5 is a cross-sectional view of an embodiment of a container for thebattery module for use in the vehicle of FIG. 1, in accordance with thepresent techniques;

FIG. 6 is a cross-sectional view of another embodiment of a containerfor the battery module for use in the vehicle of FIG. 1, in accordancewith the present techniques;

FIG. 7 is a cross-sectional view of another embodiment of a containerfor the battery module for use in the vehicle of FIG. 1, in accordancewith the present techniques;

FIG. 8 is a cutaway perspective view of an embodiment of a prismaticelectrochemical cell, in accordance with the present techniques;

FIG. 9 is a cutaway perspective view of an embodiment of a cylindricalelectrochemical cell, in accordance with the present techniques;

FIG. 10 is a cross-sectional view of an embodiment of a housing for usein the prismatic electrochemical cell of FIG. 8, in accordance with thepresent techniques;

FIG. 11 is a cross-sectional view of another embodiment of a housing foruse in the prismatic electrochemical cell of FIG. 8, in accordance withthe present techniques;

FIG. 12 is a partial cross-sectional view of a portion of an embodimentof a housing being welded for use in the prismatic electrochemical cellof FIG. 8, in accordance with the present techniques;

FIG. 13 is a cross-sectional view of an embodiment of the battery modulefor use in the vehicle of FIG. 1, in accordance with the presenttechniques; and

FIG. 14 is a cross-sectional view of another embodiment of the batterymodule for use in the vehicle of FIG. 1, in accordance with the presenttechniques.

DETAILED DESCRIPTION

The battery systems described herein may be used to provide power tovarious types of electric vehicles and other high voltage energystorage/expending applications (e.g., electrical grid power storagesystems). Such battery systems may include one or more battery modules,each battery module having a number of battery cells (e.g., lithium ion(herein “Li-ion”) electrochemical cells) containing cell elementsarranged to provide particular voltages and/or currents useful to power,for example, one or more components of an xEV. In accordance with thepresent disclosure, polymeric (e.g., plastic) materials may be used fora portion of each battery module (e.g., a container formed by thebattery module) and/or a portion of each Li-ion electrochemical cell(e.g., a housing of the Li-ion electrochemical cell surrounding the cellelement). By using polymeric housings and/or containers, production costis reduced compared to traditional Li-ion battery modules that includeexpensive and harder to form metal materials. Plastic housings andcontainers enable lower piece price, lower tooling costs, shorter leadtimes, reduced part quantities, and greater processing flexibility andefficiency. For example, a traditional metal housing for a cell elementmay include a non-conducting sleeve around the metal housing to preventelectrical shorts. Processing the traditional metal housing and sleeveseparately may lengthen the manufacturing process and increase thenumber of parts for the battery module, both of which may increaseproduction cost. Using polymeric materials for the housing may reduceproduction cost and time. Additionally, polymeric materials enableinjection molding around non-polymeric materials, such as to addressthermal control issues. Certain polymeric formulations and/or coatingsmay be used to address permeability issues and/or thermal conductivity.

With the foregoing in mind, the Li-ion electrochemical cells (or cellelements) of each battery module may generate heat, which may cause thebattery modules to operate at an elevated temperature. For example,battery modules of the present disclosure may operate at temperatures upto 85° Celsius. Traditional molded polymers may be poor thermalconductors. Additionally, traditional molded polymers may be susceptibleto water, oxygen, hydrocarbon/organic carbonate, and/or electrolytemigration or permeability that may negatively affect the Li-ionelectrochemical cells. Accordingly, there is a need for improved thermalmanagement and permeability management of battery systems with polymerbased housings and/or battery modules (e.g., containers), in order toproduce the battery modules at reduced costs and with greaterefficiency.

Presently disclosed embodiments are directed to polymer (e.g., plastic)battery systems that include various features to promote thermalmanagement and impermeability of the polymer battery components. In someembodiments, each Li-ion electrochemical cell may include features thataddress thermal management and permeability management concerns. Inother embodiments, the battery module and its associated elements (e.g.,the container formed by the battery module) may include features thataddress thermal management and permeability management concerns. Instill other embodiments, each Li-ion electrochemical cell and thebattery module may both include features that address thermal managementand permeability management concerns. In accordance with the presentdisclosure, thermal management and/or permeability management concernsmay be addressed at the cell and/or module level by using polymeric cellhousings and/or module containers with nanomaterial additives, usingthermally enhanced polymeric composite housings and/or containers,metalizing the outside and/or inside of housings and/or containers(e.g., metalizing with aluminum), and/or using polymeric housings and/orcontainers with molded-in heat sink plates. Nanomaterial additives,metalized surfaces, and molded in heat sinks enable sufficient thermalmanagement and permeability management that may arise from concernsassociated with using plastic materials. Additionally, in accordancewith the present disclosure, laser welding and/or ultrasonic weldingtechniques may be adapted to enhance and enable impermeability of cellsand battery modules that include a polymer (e.g., plastic) base materialwith additives, nanosupplements, and/or metalized layers.

With the foregoing in mind, FIG. 1 is a perspective view of an xEV 10 inthe form of an automobile (e.g., a car) having a battery system (e.g., aLi-ion battery system 12) in accordance with present embodiments forproviding a portion of the motive power for the vehicle 10, as describedabove. Although the xEV 10 may be any of the types of xEVs describedabove, by specific example, the xEV 10 may be a mHEV, including aninternal combustion engine equipped with a microhybrid system whichincludes a start-stop system that may utilize the Li-ion battery system12 to power at least one or more accessories (e.g., AC, lights,consoles, etc.), as well as the ignition of the internal combustionengine, during start-stop cycles.

Further, although the xEV 10 is illustrated as a car in FIG. 1, the typeof vehicle may differ in other embodiments, all of which are intended tofall within the scope of the present disclosure. For example, the xEV 10may be representative of a vehicle including a truck, bus, industrialvehicle, motorcycle, recreational vehicle, boat, or any other type ofvehicle that may benefit from the use of electric power. Additionally,while the battery system 12 is illustrated in FIG. 1 as being positionedin the trunk or rear of the vehicle, according to other embodiments, thelocation of the battery system 12 may differ. For example, the positionof the battery system 12 may be selected based on the available spacewithin a vehicle, the desired weight balance of the vehicle, thelocation of other components used with the battery system 12 (e.g.,battery control units, measurement electronics, etc.), and a variety ofother considerations.

In some embodiments, the xEV 10 may be an HEV having the battery system12, which includes one or more battery modules 13, as illustrated inFIG. 2. In particular, the battery system 12 illustrated in FIG. 2 isdisposed toward the rear of the vehicle 10 proximate a fuel tank 14. Inother embodiments, the battery system 12 may be provided immediatelyadjacent the fuel tank 14, provided in a separate compartment in therear of the vehicle 10 (e.g., a trunk), or provided in another suitablelocation in the HEV 10. Further, as illustrated in FIG. 2, the HEV 10includes an internal combustion engine 16 for times when the HEV 10utilizes gasoline power to propel the vehicle 10. The HEV 10 alsoincludes an electric motor 18, a power split device 20, and a generator22 as part of the drive system.

The HEV 10 illustrated in FIG. 2 may be powered or driven by the batterysystem 12 alone, by the combustion engine 16 alone, or by both thebattery system 12 and the combustion engine 16. It should be noted that,in other embodiments of the present approach, other types of vehiclesand configurations for the vehicle drive system may be utilized, andthat the schematic illustration of FIG. 2 should not be considered tolimit the scope of the subject matter described in the presentapplication. According to various embodiments, the size, shape, andlocation of the battery system 12 and the type of vehicle, among otherfeatures, may differ from those shown or described.

One embodiment of a suitable battery module 13 is illustrated in anexploded perspective view in FIG. 3. As shown, the battery module 13includes a plurality of Li-ion battery cells 24 that are containedwithin a battery module shell 26. According to an embodiment, the cellsinclude at least one terminal, such as a positive terminal 28 and/or anegative terminal 30.

The Li-ion battery cells 24 in the illustrated embodiment are providedside-by-side one another such that a face of the first Li-ion batterycell 24 is adjacent a face of the Li-ion second battery cell 24 (e.g.,the cells face one another). According to the illustrated embodiment,the Li-ion cells 24 are stacked in an alternating fashion such that thepositive terminal 28 of the first cell is provided adjacent the negativeterminal 30 of the second cell. Likewise, the negative terminal 30 ofthe first cell 24 is provided adjacent a positive terminal 28 of thesecond cell 24. Such an arrangement allows for efficient connection ofthe Li-ion battery cells 24 in series via bus bars. However, the Li-ionbattery cells 24 may be otherwise arranged and/or connected (e.g., inparallel, or in a combination of series and parallel) in otherembodiments.

In the illustrated embodiment, the battery module shell 26 for thebattery module 13 includes a first side bracket 34 and a second sidebracket 36. The shell 26 further includes a first end cap 38 and asecond end cap 40. As shown, the end caps 38 and 40 are secured to theside brackets 34 and 36, respectively. The Li-ion battery cells 24 maybe generally prismatic lithium-ion cells, as shown in the illustratedembodiment. According to other embodiments, the Li-ion battery cells 24may have other physical configurations (e.g., oval, cylindrical,polygonal, etc.). Additionally, in some embodiments, the capacity, size,design, and other features of the Li-ion battery cells 24 may differfrom those shown.

Each Li-ion battery cell 24 includes a housing 44 (e.g., a can orcontainer) through which the battery terminals 28 and 30 extend.Accordingly, it should be noted that each Li-ion battery cell 24 refersto a complete battery cell with a Li-ion battery cell element 45contained within the housing 44. In certain embodiments of the presentdisclosure, each Li-ion battery cell element 45 may be contained withinthe battery module 13 without the housing 44. In such embodiments,elements of the battery module 13 (e.g., partitioning elements) may beutilized to electrically isolate portions of each Li-ion battery cellelements 45 from one another. Thus, “Li-ion battery cell 24” referred toforthwith relates to a complete battery cell including the housing 44,and “Li-ion battery cell element 45” or “cell element 45” refers to thejelly-roll shaped cell element 45 (e.g., wound or stacked electrodes)that may be placed within the housing 44 to form the complete Li-ionbattery cell 24 (which may in turn be used in the battery module 13), ormay be included directly in the battery module 13 without the housing44.

In the illustrated embodiment, each Li-ion battery cell 24 includes afill hole 46 through the housing 44 for introducing electrolyte into thebattery cell 24, such that the battery cell element 45 of the batterycell 24 is immersed in electrolyte. In present embodiments, the housing44 may be a polymeric (e.g., plastic) housing 44 formed via an injectionmolding process. In particular, the housing 44 may be an electricallynon-conductive polymeric housing 44.

In some embodiments, the battery module 13 may include fewer or moreLi-ion battery cell elements 45 than shown in FIG. 3. Additionally, insome embodiments, each battery cell element 45 may be placed directlyinto the battery module 13, without the housing 45 around each batterycell element 45. For example, in FIG. 4, a partially explodedperspective view of an embodiment of the battery module 13 is shown withtwo Li-ion battery cell elements 45. However, the features of thebattery module 13 shown in FIG. 4 may apply to a battery module 13having more than two Li-ion battery cell elements 45.

In the illustrated embodiment, the battery module 13 includes acontainer 60 with two cell elements 45 separated by a partition 62. Thebattery module 13 also includes a lid 64 (or cover) with two terminals66, 68. These terminals 66, 68 may be coupled to end terminals 28, 30 ofthe Li-ion battery cell elements 45 coupled together in series and/or inparallel within the container 60. The lid 64 also includes electrolytefill holes 46, one over each Li-ion battery cell element 45, such thatelectrolyte may be introduced into the container 60 and each cellelement 45 is immersed in electrolyte. Additionally, each cell element45 in the illustrated embodiment is exposed within the container 60. Inother words, the cell elements 45 do not include individual housings(e.g., housings 44 in FIG. 3). In this example, each cell element 45, aspreviously described, forms a jelly roll shape (e.g., wound or stackedelectrodes), and each cell element 45 fits into an individualcompartment 72 in the battery module 13, where the compartments 72 areseparated by the partition 62. In certain embodiments, the container 60of the battery module 13 may include multiple partitions 62, such thatthe container 60 includes three or more compartments 72 for three ormore cell elements 45. Each partition 62 electrically isolates the cellelements 45, except for an electrical connection between the cellelements 45 via electrical connectors 74. For example, each cell element45 may include electrical connectors 74 on either end. The electricalconnectors 74 are configured to electrically couple the cell elements 45in parallel or in series. The electrical connectors 74 may extend fromthe terminal 28 of one cell element 45 to the terminal 30 of anothercell element 45 by extending over the partition 62 and under the lid 64,over the partition and through the lid 64 (e.g., partially embeddedwithin the lid 64), or through an aperture in the partition 62.Additionally, each compartment 72 may contain electrolyte introducedinto the container 60 through the electrolyte fill holes, as previouslydescribed. Once filled with electrolyte, sealed, and isolated, the twocell elements 45 form two Li-ion battery cells 24 in the module 13.

In some embodiments, the container 60 of the battery module 13 may notinclude the partition 62. In such embodiments, each individual cellelement 45 may include the housing 44 to form the Li-ion battery cell24, as previously described with reference to FIG. 3. Accordingly, thehousing 44 is configured to electrically isolate the cell element 45from other cell elements 45. In other words, in some embodiments, thepartition 62 may be included to electrically isolate cell elements 45.In other embodiments, the container 60 may not include the partition 62,but each cell element 45 may include the housing 44 to electricallyisolate each cell element 45 from one another. One such embodiment ofthe container 60 without the partition 62 is shown in FIG. 5, which is across-sectional view an embodiment of the battery module 13 includingthe container 60 configured to retain Li-ion battery cells 24. In theillustrated embodiment, the battery module 13 includes the container 60and the cover 64, and the cover 64 includes the electrolyte fill holes46 configured to align with electrolyte fill holes 46 of the cells 24.The electrolyte fill holes 46 may or may not be included in thecontainer 60, as each Li-ion battery cell 24 may have electrolyteintroduced into the cell 24 through fill holes 46 in the housing 44before being placed in the container 60. Although the illustratedembodiment of the container 60 is configured to hold two Li-ion batterycells 24, other containers 60 in accordance with the present embodimentmay include three or more Li-ion battery cells 24. It should be notedthat features of the container 60 described below (with reference toFIGS. 5-7) may apply to the container 60 without the partition 62 (e.g.,as shown in the illustrated embodiments) and to the container 60 withthe partition 62.

In the illustrated embodiment, the container 60 with the cover 64 isformed by an electrically nonconductive polymeric (e.g., plastic)material. By using a moldable polymer (e.g., plastic) instead of ametal, the container 60 may be injection molded into its final shape andmay serve to electrically isolate the Li-ion battery cells 24 heldtherein. In some embodiments, the polymer may be a moldable, heatsealable material that exhibits resistance to water migration,resistance to oxygen migration, resistance to hydrocarbon/organiccarbonate migration, resistance to electrolyte migration, or two or moreof these. For example, polypropylene or polyphenylene sulfide (PPS) maybe used as a water and/or chemical permeability barrier. However,polypropylene, PPS, and other polymers (e.g., polyimide, polyamide,polyethylene (PET), etc.) may not be sufficiently effective inpreventing oxygen and certain fluid migration over the life time of theLi-ion battery cell 24 housed within the container 60, and thus may bereinforced with supplemental additives configured to prevent suchmigration.

Accordingly, nanomaterials may be used to supplement polymer basedcontainers 60 of the battery modules 13 in accordance with the presentdisclosure. For example, materials such as silicate nanocomposites(e.g., exfoliated montmorillonite clay), nanocellulosic fibers, orindividual or mixed nanometallic oxides may be blended with the polymerto form a composite 76, where the composite 76 is injection molded toform the container 60. In some embodiments, the nanomaterial(s) may becoated onto the polymer and co-extruded in dual or multiple layers. Forexample, the nanomaterial may be layered (e.g., by spraying thenanomaterial) over a polymer sheet or between two polymer sheets to forma multi-layer sheet, where the multi-layer sheet is injection moldedand/or formed into the shape of the container 60. In some embodiments,the nanomaterial (e.g., nanosupplements) may be applied as films orcoatings over a pre-formed polymer container 60. For example, thecontainer 60 may be formed first, and the nanomaterial may be sprayedonto the container 60 after the container 60 is formed.

In any of the above described embodiments utilizing a polymer base withnanomaterial additives, the container 60 may be cheaper and more easilymanufactured than it would be using traditional metal canconfigurations. For example, as described above, the polymer material ischeaper than most metals, and enables the container 60 to be injectionmolded into its final shape for a more efficient production method.Additionally, the container 60 may be injection molded around orintegrally with other elements, such as a metal heat sink plate forthermal management, which will be described in detail with reference tolater figures. Further, by utilizing nanomaterials in conjunction withthe polymer base to form a nanocomposite, the container 60 may exhibitenhanced impermeability properties relative to polypropylene, PPS, orother polymers alone.

The composite 76 material may also be formed by a polymer base withadditives used for enhanced thermal management. In accordance with thepresent disclosure, certain components of the Li-ion cells 24 operatebest at temperatures between approximately 0 and 50° C. However, in someembodiments, the Li-ion cells 24 may and their associated battery module13 may reach temperatures of up to approximately 85° C. Accordingly,additives blended with the polymer base may enable increased thermalmanagement of the Li-ion cells 24 and battery module 13. Morespecifically, the additives may be materials that have higher thermalconductivities than the base polymer alone. Thus, when added to the basepolymer, the additive(s) may increase the overall thermal conductivityof the container 60. As a result, the composite container 60 may moreeasily transfer heat away from heat-sensitive components of the batterymodule 13 and toward a heat sink or other cooling system of the batterymodule 13.

The composite 76 in the illustrated embodiment may include thermallyconductive additives such as alumina (e.g., aluminum oxide), aluminum,brass, graphite, magnesium oxide, stainless steel, calcium carbonate,acetylene black, and/or glass. The additives may include flakes, fibers,powder, and/or microspheres added to the polymer (e.g., plastic) base.Thermal conductivity values for certain additives are in Table 1 shownbelow:

TABLE 1 Thermal Conductivity at Room Composite Material TemperatureUnfilled plastic polymers 0.17-0.35 W/mK Polyimide + 40% graphite 1.7W/mK Rubber + Aluminum Oxide (Al₂O₃) 0.6 W/mK Rubber + Aluminum flakes1.0 W/mK

Additionally, certain commercially available products that includeelectrically non-conducting polymer plastics may also offer desirablethermal conductivity. For example, certain COOLPOLY® D-series dielectricplastics generally include additives to enhance thermal conductivity andmay offer up to 10 W/mk thermal conductivity. In other words, certainCOOLPOLY® D-series dielectric plastics may be polymer blends orcomposites and may be used alone or may include additional additivesdescribed above. Additionally, COOLPOLY® D-series dielectric plastics(e.g., polymer blends or composites) may offer up to 10 W/mk orapproximately 5-100 times the thermal conductivity of an unfilledplastic polymer. These dielectric plastics, other composite materialsshown in Table 1, or other thermally conductive and electricallyisolative polymers may be used to enhance the thermal conductivity ofthe housing 44 or the battery module 13 with the container 60.

In some embodiments, the container 60 may be formed using a moldablepolymer material, as previously described, but in conjunction with ametallized coating on an inside of the battery module 13 for enhancedthermal management and/or permeability management. The metalized coatingmay include a pure metal, a metal alloy, a metal oxide, or a metalnitride. For example, the metalized coating may be an aluminized layer.In particular, the aluminized layer may be pure aluminum, an aluminumalloy, aluminum oxide, or aluminum nitride. Other metals (e.g. in theform of pure metals, metal alloys, metal oxides, or metal nitrides) thatmay be used include copper, steel, and nickel.

For example, FIG. 6 is a cross-sectional view of an embodiment of thebattery module 13 having the container 60, where the container 60 ismade with a polymeric material, such as polypropylene, PPS, or someother plastic. In the illustrated embodiment, the container 60 is coatedon an inner wall 80 of the container 60 with an aluminized layer 82. Thealuminized layer 82 may be added by sputtering a thin film onto theinner wall 80 of the container 60. The container 60 with the aluminizedlayer 82 may exhibit both enhanced thermal management properties andenhanced permeability properties. In other words, the aluminized layer82 in the illustrated embodiment serves to extract heat from cellelement 45 as well as block gasses and liquid from egress out of oringress into the container 60. The aluminized layer 82 may extract heatfrom each cell element 45, and the heat may be spread evenly throughoutthe container 60 of the battery module 13. Thus, particular areas of thecontainer 60 (e.g., particular cell elements 45 in the container 60) maynot experience heat differentials relative to other areas of thecontainer (e.g., other cell elements 45 in the container). Additionally,the aluminized layer 82 may block the electrolyte inside the container60 from permeating the container 60. Additionally, it should be notedthat some other metal (e.g., pure metal, metal alloy, metal oxide, ormetal nitride) capable of being added by sputtering a thin film orcoating a thin film or layer on an inside of the container 60 may alsobe used for permeability and/or thermal management, as described above.

In some embodiments, techniques and features from the embodiments inFIGS. 5 and 6 may be used in combination. For example, in FIG. 7, anembodiment of the battery module 13 in accordance with the presentdisclosure is shown in a cross-sectional illustration. In theillustrated embodiment, the container 60 is formed with a composite 76including a polymer base (e.g., polypropylene, PPS, or polyimide). Thecomposite 76 may also include a nanomaterial to address permeabilityconcerns (e.g., to combat ingress and egress of gases and/or liquids),as described with reference to FIG. 5, an additive for generating athermally enhanced polymer, as described with reference to FIG. 5, or acombination of both. The container 60 may include an aluminum (or someother metal) layer 82 that may be coated on the inside surface 80 of thecontainer 60, as described with reference to FIG. 6. In someembodiments, the composite 76 may make the container impermeable toundesired liquids and gases, while the aluminum layer 82 may enhancethermal management and/or provide additional permeability control. Inother embodiments, the composite 76 may enhance thermal management andthe aluminum layer 82 may make the container impermeable to undesiredliquids and gases. Accordingly, the resulting battery module 13 mayinclude a moldable base polymer material that exhibits enhanced thermalmanagement and enhanced permeability management at a reduced cost andwith more flexible production methods (e.g., injection molding) thanconfigurations that utilize an expensive metal material for thecontainer 60.

In accordance with the present disclosure, similar techniques andmaterials as those described above (with reference to the batterymodules 13) may be utilized to enhance thermal management andpermeability management for each individual Li-ion battery cell 24. Asdiscussed above, the container 60 of the battery module 13 may includecost-effective features that enable enhanced thermal management andpermeability management of a polymer based battery system 12. Inaddition to, or in lieu of these features, the Li-ion battery cells 24may include cost-effective features that enable enhanced thermalmanagement and permeability management of the polymer (e.g., plastic)based battery system 12 as well. For example, an embodiment of anindividual, prismatic Li-ion battery cell 24 is shown in a cutawayperspective view in FIG. 8. In the illustrated embodiment, theindividual Li-ion battery cell 24 includes a jelly roll shaped Li-ionelectrochemical element 45 enclosed by a polymer (e.g., plastic) basedhousing 44. The polymer based housing 44 may be used instead of metalbecause it is cheaper and electrically insulates the Li-ion battery cell24 from a surrounding environment 90. The polymer alone, however, maynot exhibit sufficient thermal management and/or permeability managementproperties. Accordingly, nanomaterials, additives, and other techniquesand/or features described above may be applied to the housing 44 of theLi-ion battery cell 24.

Additionally, the polymer based housing 44 of the Li-ion battery cell 24(e.g., enclosing the cell element 45) may be metalized on an externalsurface 92 of the housing 44, as shown in the illustrated embodiment. Inanother embodiment, the polymer based housing 44 of the Li-ion batterycell 24 may be metalized on an internal surface 94 of the housing 44. Ineither configuration, the metallization enables a metalized layer 96 tocontrol permeability of the individual Li-ion battery cell 24. Forexample, the metalized layer 96 on the external surface 92 of thehousing 44 may block ingress of moisture, gases, and/or other fluids orliquids through the polymer based housing 44 into the Li-ion batterycell 24. The metalized layer 96 on the internal surface 94 of thehousing 44 may block egress of electrolyte through the polymer basedhousing 44 to the surrounding environment 90. In both configurations,the polymeric material of the housing 44 is protected from fluidssaturating and/or negatively affecting the housing 44, and fluids areisolated from entering or exiting from inside the Li-ion battery cell24. Additionally, in some embodiments, the housing may include themetalized layer 96 on the internal surface 94 of the housing 44 and themetalized layer 96 on the external surface 92 of the housing 44 to blockboth egress of electrolyte and ingress of moisture, gases, and/or otherfluids.

The Li-ion battery cell 24 may include one or more terminals 28extending through an opening in the housing 44 and the metalized layer96. A plastic seal ring 100 may be disposed around each terminal 28. Theplastic seal ring 100 may extend from the housing 44 and through themetalized layer 96, such that the plastic seal ring 100 electricallyisolates the terminal 28 from the metalized layer 96. The plastic sealring 100 may also serve to seal the opening in the housing 44 throughwhich the terminal 28 extends. The plastic seal ring 100 may bethermally shrink fit or crimped around the terminal 28, welded to theterminal 28 via laser or ultrasonic welding, or coupled to the terminal28 in some other manner

The above described techniques may also apply to a Li-ion battery cell24 that is not prismatic. For example, an embodiment of a cylindricalLi-ion battery cell 24 is shown in a cutaway perspective view in FIG. 9.In the illustrated embodiment, the metalized layer 96 is disposed on theexternal surface 92 of the housing 44, but may be disposed on theinternal surface 94 of the housing 44 in other embodiments. Aspreviously described, the housing 44 may include a polymer (e.g.,plastic) base with nanomaterial supplements and/or other thermallyenhancing additives. The metallization surface 96 may serve as apermeability barrier and/or thermal management surface. As previouslydescribed, the metalized layer 96 may be applied to both the externalsurface 92 and the internal surface 94 of the housing 44.

In order to enable a full permeability barrier for each individualLi-ion battery cell 24 and/or the container 60 of the battery module 13holding the cells 24, welding techniques may be used to seal elements ofthe housing 44 of the Li-ion battery cell 24 or the container 60. Forexample, an embodiment of the individual Li-ion battery cell 24 with theprismatic shape is shown in a cross-sectional view in FIG. 10. In theillustrated embodiment, the housing 44 of the Li-ion battery cell 24 maybe enhanced by nanomaterials or other additives, as described above.Additionally, the housing 44 may have the metalized surface 96.

The Li-ion battery cell 24 includes the cover 64 disposed in an openingof the housing 44 opposite a top 106 of the housing 44. In other words,the cover 64 may form a bottom 108 of the housing 44. Additionally, anouter wall 109 (e.g., a side wall) may extend from the top 106 to thebottom 108 of the housing 44, and the outer wall 109 may form aprismatic body of the Li-ion battery cell 24. The outer wall 109 mayextend in an ovular or curved manner around the cell element 45, betweenthe top 106 and the bottom 108 (e.g., the cover 64) of the housing 44.

In the illustrated embodiment, the cover 64 is made from a transmissivematerial (e.g., relative to heat and/or light) and the outer wall 109 ofthe housing 44 is made of an absorptive material (e.g., relative to heatand/or light). The transmissive material generally refers to a materialconfigured to allow light and/or heat from a heat source to pass throughit, while the absorptive material generally refers to a materialconfigured to absorb heat from the heat source. For example, thetransmissive material may be substantially an unfilled grade of PPS,while the absorptive material may PPS based with glass and carbonadditives.

In the illustrated embodiment, components formed by the absorptivematerial are configured to absorb heat and melt into the transmissivematerial. For example, a laser welding tool 110 may transmit lightand/or heat via a laser through the transmissive material of the cover64 to the absorptive material of the outer wall 109. The outer wall 109absorbs heat from the laser welding tool 100 and melts into the cover64, thereby welding the cover 64 to the housing 44. It should be notedthat, given the same position of the laser welding tool 110 shown in theillustrated embodiment, the cover 64 may be made of the absorptivematerial and the outer wall 109 may be made of the transmissivematerial. In other words, the laser welding tool 110 may apply heatdirectly to the cover 64, such that the cover 64 absorbs heat from thelaser welding tool 110 and melts into the outer wall 109. Upon meltinginto the outer wall 109, the cover 64 seals the bottom 108 of thehousing to block ingress of moisture into the housing 44 and blockegress of electrolyte out of the housing 44.

In another embodiment, the laser welding tool 110 may be positionedadjacent to the outer wall 109. For example, an embodiment of the Li-ionbattery cell 24 in accordance with the present disclosure is illustratedin a cross-sectional view in FIG. 11. In this embodiment, the outer wall109 may be made from a transmissive material while the cover 64 is madefrom an absorptive material. In the illustrated embodiment, the laserwelding tool 110 is positioned such that the laser is directed throughthe outer wall 109. A lip 120 that extends around a perimeter of thecover 64 is configured to fit inside the outer wall 109 of the housing44. Thus, in the illustrated embodiment, the laser welding tool directsthe heat from the laser through the transmissive material of the outerwall 109 to the lip 120 of the cover 64, melting the lip 120 into theouter wall 109. As previously described, in another embodiment, theouter wall 109 may be the absorptive material and the cover 64 may bethe transmissive material. Accordingly, the outer wall 109 may absorbheat from the laser welding tool 110 and melt directly into the lip 120of the cover 64.

In the embodiments discussed with reference to FIGS. 10 and 11, thetransmissive and absorptive materials may include a polymer (e.g.,plastic) base, as previously described. Additionally, the absorptivematerial may include glass and carbon additives. For example, theabsorptive material may include approximately 20% glass andapproximately 0.5% carbon additive. The transmissive material may besubstantially an unfilled grade of PPS. Thus, it may be desirable toinclude a transmissive material for the cover 64, such that fillersand/or additives may be added to the housing 44 (which generallyincludes a greater volume than the cover 64) for enhanced thermalmanagement and permeability management, as previously described.However, in another embodiment, both the housing 44 and the cover 64 mayinclude additives for enhanced thermal management and permeabilitymanagement. In such embodiments, a portion of the cover 64 or housing 44that serves as a welding surface may not include additives. For example,the cover 64 may be graded such that the lip 120 does not includeadditives while all other portions of the cover 64 do include additives.As such, the lip 120 may be an unfilled grade of PPS or some otherpolymer, such that the lip 120 includes the transmissive material, asdescribed above. Thus, the housing 44 and the cover 64 together offerthermal and/or permeability management around the entirety of the cell24.

It should be noted that, due to sensitivity of electrolyte used in theLi-ion battery cells 24, materials for material selection for the cover64 and the housing 44 may be limited compared to materials for materialselection for elements in other battery systems. Indeed, materialselection for any of the above described features and/or techniquesregarding the battery module 13 forming the container 60 and theindividual Li-ion battery cells 24 is constrained by the electrolytecomposition used in lithium ion applications. Accordingly, the materialselection described above may enable the laser welding techniquesdescribed above, and the materials and techniques of the presentdisclosure may be tailored for use in Li-ion battery cell 24 and Li-ionbattery system applications.

Ultrasonic welding techniques may also be used for sealing the cover 64to the outer wall 109 of the housing 44. For example, a portion of anembodiment of the Li-ion battery cell 24 (e.g., the housing 44) beingsealed via ultrasonic welding is shown in FIG. 12. In the illustratedembodiment, the outer wall 109 includes a ridge 126 that contacts thecover 64. The ridge 126 may extend with the outer wall 109 around theLi-ion battery cell 24. The ridge 126 may be disposed over small ridges128 of the cover 64. The small ridges 128 of the cover may extendbetween the lip 120 of the cover 64 and an outermost perimeter 130 ofthe cover 64. The small ridges 128 of the cover 64 may be disposed suchthat they are oriented substantially perpendicular to the ridge 126 ofthe outer wall 109.

In the illustrated embodiment, the small ridges 128 and the ridge 126may be energy directors for an ultrasonic welding tool 132. In someembodiments, the ultrasonic welding tool 132 may be a torsionalultrasonic welding tool 132. In the present embodiment, the ultrasonicwelding tool 132 may be positioned adjacent to and/or in contact withthe cover 64. The ultrasonic welding tool 132 may emit high-frequencyultrasonic acoustic vibrations that are locally applied while the cover64 and the outer wall 109 of the housing 44 are pressed together. Thevibrations may cause a solid-state weld to form between the outer wall109 and the cover 64. The energy directors (e.g., the small ridges 128of the cover 64 and the ridge 126 of the outer wall 109) may focusenergy at the edges of the small ridges 128 and the ridge 126 to urgethe outer wall 109 and the cover 64 to join together, where the edgesmay form a 60-90° angle. The ridges may melt down such that the cover 64and the outer wall 109 are joined and sealed without major crevices orirregular protrusions. It should be noted that, in some embodiments, thecover 64 might not include the small ridges 128, but rather a smoothsurface. The materials of the outer wall 109 and the cover 64 may be thesame as those used in the laser welding techniques described above, orthe materials may be different. For example, the materials may includeadditives and/or nanomaterials as previously described with reference toprevious embodiments. Additionally, in some embodiments, the ridge 126may be disposed on the cover 64 and the small ridges 128 may be disposedon the outer wall 109.

It should be noted that the welding techniques discussed above (e.g.,laser welding and ultrasonic welding) may apply to welding of the cover64 to the container 60 of the battery module 13. In other words, thewelding techniques may apply to sealing the individual Li-ionelectrochemical cells 24, the welding techniques may apply to sealingthe container 60, or the welding techniques may apply to sealing theindividual electrochemical cells 24 and the container 60. The weldingtechniques may generate a weld configured to block moisture fromingressing into the battery module 13 and/or configured to blockelectrolyte from egressing out of the battery module 13.

In accordance with the present disclosure, the above referencedtechniques, features, and/or materials may be utilized for the Li-ionbattery cell 24, the battery module 13 with the container 60, or both.In additional to the above referenced techniques and materials, a heatsink may be included in the container 60 of the battery module 13 and/orhousing 44 of the Li-ion battery cell 24 (e.g., the housing 44 aroundthe cell element 45). For example, FIG. 13 is a cross-sectional view ofan embodiment of the battery module 13 having a U-shaped heat sink 140molded into the container 60 of the battery module 13. The U-shaped heatsink 140 may have a U-shaped cross-sectional profile including a firstleg 142, a second leg 144, and a connecting base member 146. The firstleg 142 and the second leg 144 may extend into portions of the container60 of the battery module 13 or housing 44 of the Li-ion battery cell 24,depending on the embodiment, and the connecting base member 146 may beexposed to atmosphere (e.g., the environment 90). The container 60 orhousing 44, or a combination of both, includes a polymer (e.g., plastic)base material, as previously described, and may have any of theadditives and/or nanosupplements described above. The container 60 mayhave the partition 62 configured to electrically isolate the cellelements 45. The cell elements 45 may, however, be electricallyconnected in series or parallel via the electrical connectors 74, aspreviously described.

The container 60 in the illustrated embodiment may have the U-shapedheat sink 140 molded into the walls of the container 60, which may beenabled by the previously described material selection of the container60. The molded in U-shaped heat sink 140 may be configured to extractheat from the cell elements 45 and/or the container 60 holding the cellelements 45 and the container 60. The U-shaped heat sink 140 in theillustrated embodiment spans two cell elements 45. In anotherembodiment, the U-shaped heat sink 140 may span one cell element 45,three cell elements 45, or more than three cell elements 45, dependingon a desired thermal management of the battery module 13. Further,multiple U-shaped heat sinks 140 may be used in a single battery module13, and the U-shaped heat sinks 140 may be integrally formed togethersuch that one leg of a first U-shaped heat sink 140 makes up one leg ofa second U-shaped heat sink 140.

It should be noted that the U-shaped heat sink 140 may be disposedwithin and retained by the housing 44 of each individual Li-ion batterycell 24 (e.g., the housing 44 around each cell element 45). For example,the U-shaped heat sink 140 may extend into an outer portion of thehousing 44, e.g., side walls of the housing 44. Additionally, any of theabove referenced techniques for permeability management and/or thermalmanagement, in accordance with the present disclosure, may be used inconjunction with the U-shaped heat sink 140, whether the U-shaped heatsink 140 is retained by the housing 44 of the Li-ion battery cell 24 orthe container 60 of the battery module 13.

Additionally, the heat sink may not be U-shaped. For example, FIG. 14 isa cross-sectional view of an embodiment of the battery module 13 havingthe container 60 with L-shaped heat sinks 150. In the illustratedembodiment, each L-shaped heat sink 150 spans one cell element 45. Inanother embodiment, each L-shaped heat sink 150 may span two or morecell elements 45. Additionally, a vertical heat sink element 152 may bedisposed at an end of the battery module 13 forming the container 60such that each cell element 45 has an equal surface area adjacent to theheat sinks. In other words, the vertical heat sink element 152 ensuresthat the outermost cell element 45 has a heat sink element adjacent toits outermost surface. However, in another embodiment, the batterymodule 13 may include L-shaped heat sinks 150 across each of the cellelements 45 except for the cell element 45 farthest to the right (e.g.,from the perspective of the illustrated embodiment). The furthest cellelement 45 to the right may include a U-shaped heat sink 140, aspreviously described, such that it has equal heat sink coverage as theother cell element(s) 45, without needing the vertical heat sink element152 as previously described.

It should be noted that the U-shaped heat sinks 140 and the L-shapedheat sinks 152 may be descriptive of the cross-sectional views in FIGS.13 and 14, but that the U-shaped heat sinks 140 and the L-shaped heatsinks 152 may actually extend around the container 60 of the batterymodule 13 and/or the housing 44 of the Li-ion battery cell 24. In otherwords, the U-shaped heat sinks 140 together and the L-shaped heat sinks152 together may extend into and out of the presently illustratedcross-sectional views to form an open prismatic container (e.g., open ata top of the heat sinks) that is molded into the container 60. Thus, agreater surface area of the Li-ion battery cells 24 is adjacent to theheat sinks 140, 150 for greater heat extraction. Further, a bottom 154of the U-shaped heat sink 140 (e.g., the connecting base member 146)and/or the L-shaped heat sink 150 in each respective embodiment may beexposed to the environment 90 such that an active cooling agent may passover the bottom 154 for active cooling. For example, a fan may blow airor a pump may pump cooling fluid over the bottom 154 for enhanced heatextraction.

By using polymeric (e.g., plastic) materials for the Li-ion batterycells 24 and battery module 13 forming the container 60, productioncosts and part costs are reduced compared to configurations utilizingmetal materials. Thermal management and permeability concerns may beaddressed by including nanosupplements and additives, as well asmetalized and/or aluminized surfaces, as described above. Additionally,polymeric materials may be over molded or injection molded with a heatsink for additional thermal management.

While only certain features and embodiments of the invention have beenillustrated and described, many modifications and changes may occur tothose skilled in the art (e.g., variations in sizes, dimensions,structures, shapes and proportions of the various elements, values ofparameters (e.g., temperatures, pressures, etc.), mounting arrangements,use of materials, colors, orientations, etc.) without materiallydeparting from the novel teachings and advantages of the subject matterrecited in the claims. The order or sequence of any process or methodsteps may be varied or re-sequenced according to alternativeembodiments. It is, therefore, to be understood that the appended claimsare intended to cover all such modifications and changes as fall withinthe true spirit of the invention. Furthermore, in an effort to provide aconcise description of the exemplary embodiments, all features of anactual implementation may not have been described (i.e., those unrelatedto the presently contemplated best mode of carrying out the invention,or those unrelated to enabling the claimed invention). It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerous implementationspecific decisions may be made. Such a development effort might becomplex and time consuming, but would nevertheless be a routineundertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure, without undueexperimentation.

1. A lithium ion (Li-ion) battery cell, comprising: a prismatic housinghaving sides formed by side walls coupled to and extending from a bottomportion of the housing, wherein the housing is configured to receive andhold a prismatic Li-ion electrochemical cell element, wherein thehousing comprises an electrically nonconductive polymeric material; anda heat sink overmolded by the polymeric material of the housing suchthat the heat sink is retained in an outer portion of the sides of thehousing and is exposed along the bottom portion of the housing.
 2. TheLi-ion battery cell of claim 1, wherein the heat sink comprises aU-shaped cross-sectional profile, wherein the U-shaped cross-sectionalprofile comprises: a first leg extending into and retained by the outerportion of the sides of the housing; a second leg extending into andretained by the outer portion of the sides of the housing; and aconnecting base member, wherein the connecting base member is exposedalong the bottom portion of the housing.
 3. The Li-ion battery cell ofclaim 1, wherein the polymeric material of the housing comprises ananomaterial supplement configured to enhance impermeability of thehousing to reduce ingress of moisture into the housing, to reduce egressof electrolyte from the housing, or any combination thereof
 4. TheLi-ion battery cell of claim 1, wherein the polymeric material of thehousing comprises additives configured to increase a thermalconductivity of the housing.
 5. The Li-ion battery cell of claim 1,comprising a metalized inner surface of the housing, wherein themetalized inner surface is configured to enhance impermeability of thehousing to reduce ingress of moisture into the housing, to reduce egressof electrolyte from the housing, or both.
 6. The Li-ion battery cell ofclaim 1, comprising a metalized outer surface of the housing, whereinthe metalized outer surface is configured to enhance impermeability ofthe housing to reduce ingress of moisture into the housing, to reduceegress of electrolyte from the housing, or both.
 7. The Li-ion batterycell of claim 1, wherein the heat sink is exposed along a bottom portionof the housing to atmosphere.
 8. A lithium ion (Li-ion) battery module,comprising: a container comprising: one or more partitions extendingfrom a bottom portion of the container that define a plurality ofcompartments within the container, wherein each of the plurality ofcompartments is configured to receive and hold a prismatic Li-ionelectrochemical cell element, wherein the container comprises anelectrically nonconductive polymeric material; and a heat sinkovermolded by the polymeric material of the container such that the heatsink is retained in a first portion of the container and is exposedalong the bottom portion of the container.
 9. The Li-ion battery moduleof claim 8, wherein the heat sink comprises an L-shaped cross-sectionalprofile, wherein the L-shaped cross-sectional profile comprises: a firstleg extending into and retained by the first portion of the container; asecond leg extending substantially perpendicular from the first leg,wherein the second leg is exposed along the bottom portion of thecontainer
 10. The Li-ion battery module of claim 8, wherein the heatsink comprises a U-shaped cross-sectional profile, wherein the U-shapedcross-sectional profile comprises: a first leg extending into andretained by the first portion of the container; a second leg extendinginto and retained by a second portion of the container; and a connectingbase member, wherein the connecting base member is exposed along thebottom portion of the container.
 11. The Li-ion battery module of claim8, wherein the first portion comprises one of the partitions of thecontainer.
 12. The Li-ion battery module of claim 8, wherein the firstportion comprises a side wall of the container.
 13. The Li-ion batterymodule of claim 8, comprising a plurality of heat sinks disposedadjacent to one another, wherein each heat sink is retained in one ofthe partitions of the container or in a side wall of the container. 14.The Li-ion battery module of claim 13, wherein each of the plurality ofheat sinks is disposed around a single compartment of the plurality ofcompartments.
 15. The Li-ion battery module of claim 8, wherein the heatsink comprises multiple legs extending into and retained by thepartitions of the container such that the heat sink is disposed aroundeach of the plurality of compartments.
 16. The Li-ion battery module ofclaim 8, wherein the polymeric material of the container comprises apolymer blend having a nanomaterial mixed into a base polymer, whereinthe nanomaterial is configured to enhance impermeability of thecontainer to reduce ingress of moisture into the container, to reduceegress of electrolyte from the container, or both.
 17. The Li-ionbattery module of claim 8, comprising a metalized inner surface of eachcompartment, wherein the metalized inner surface is configured toenhance impermeability of the container to reduce ingress of moistureinto the container, to reduce egress of electrolyte from the container,or both.
 18. The Li-ion battery module of claim 8, comprising a fan orpump configured to enable active heat transfer from the exposed portionof the heat sink by moving cooled air or fluid adjacent the exposedportion.
 19. The Li-ion battery module of claim 8, wherein the heat sinkis exposed to an atmosphere along the bottom portion of the container.20. A method for manufacturing a lithium ion (Li-ion) battery module,comprising: overmolding a heat sink with an electrically nonconductivepolymeric material to form a container, wherein the container comprisesone or more partitions extending from a bottom portion of the containerthat define a plurality of compartments within the container to receiveand hold prismatic Li-ion electrochemical cell elements; wherein theheat sink is overmolded such that the heat sink is retained in a portionof the container and is exposed along the bottom portion of thecontainer.
 21. The method of claim 20, wherein the polymeric materialcomprises a polymer blend having a nanomaterial mixed with a basepolymer, wherein the nanomaterial is configured to enhanceimpermeability of the container to reduce ingress of moisture into thecontainer, to reduce egress of electrolyte from the container, or both.22. The method of claim 20, comprising: coating the polymeric materialwith metal; and overmolding the heat sink with the coated polymericmaterial.